U.S. patent application number 15/704116 was filed with the patent office on 2019-03-14 for apparatus and method for minimizing elongation in drilled holes.
This patent application is currently assigned to SPIRIT AEROSYSTEMS, INC.. The applicant listed for this patent is SPIRIT AEROSYSTEMS, INC.. Invention is credited to Gregorio Balandran, John R. Dye, Amitab Vyas.
Application Number | 20190076932 15/704116 |
Document ID | / |
Family ID | 63668299 |
Filed Date | 2019-03-14 |
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United States Patent
Application |
20190076932 |
Kind Code |
A1 |
Vyas; Amitab ; et
al. |
March 14, 2019 |
APPARATUS AND METHOD FOR MINIMIZING ELONGATION IN DRILLED HOLES
Abstract
A drilling apparatus and method for drilling holes into a
composite workpiece. The drilling apparatus may include an end
effector, a drill bit, and a control system. The end effector may
include an end effector housing, a drill bit attachment, a rotation
actuator, and a linear motion actuator. The linear motion actuator
may convert rotary motion of a rotary motor into linear motion of
the drill bit attachment. The drill bit may have a widest portion
which cuts a hole into the workpiece and a narrow flute portion
limiting contact time between the drill bit and the workpiece. The
control system may control a speed of the linear motion actuator,
with a first speed as the drill bit is plunged into the workpiece
and a second speed, slower than the first speed, as the drill bit
is retracted out of the workpiece.
Inventors: |
Vyas; Amitab; (Wichita,
KS) ; Dye; John R.; (Wichita, KS) ; Balandran;
Gregorio; (Wichita, KS) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SPIRIT AEROSYSTEMS, INC. |
Wichita |
KS |
US |
|
|
Assignee: |
SPIRIT AEROSYSTEMS, INC.
Wichita
KS
|
Family ID: |
63668299 |
Appl. No.: |
15/704116 |
Filed: |
September 14, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23B 7/06 20130101; B23B
35/00 20130101; B23B 39/14 20130101; B23B 2215/04 20130101; B23B
2251/244 20130101; B23B 2226/27 20130101; B23B 2251/248 20130101;
B23Q 17/22 20130101; B25J 11/0055 20130101 |
International
Class: |
B23B 7/06 20060101
B23B007/06; B23B 25/06 20060101 B23B025/06; B23B 3/26 20060101
B23B003/26; B23B 27/16 20060101 B23B027/16 |
Claims
1. A drilling apparatus comprising: an end effector including an
end effector housing and one or more actuators; a drill bit
attached to the end effector, wherein the drill bit includes a
forward end, an aftward end opposite the forward end, a tip formed
at the forward end, a widest portion aftward of the tip, and a
narrow flute portion aftward of the widest portion, wherein the
flute portion extends between the widest portion and the end
effector, wherein the flute portion has a smaller diameter than the
widest portion; and a control system configured to send control
signals to the actuators commanding rotation of the drill bit and
commanding movement of the drill bit laterally outward and
inward.
2. The drilling apparatus of claim 1, wherein the control system
commands at least one of the actuators to move the drill bit
laterally outward at a first speed and to move the drill bit
laterally back inward at a second speed, wherein the second speed
is faster than the first speed.
3. The drilling apparatus of claim 1, wherein the end effector
includes a drill bit attachment configured for clamping the drill
bit centrally therein.
4. The drilling apparatus of claim 3, wherein the actuators of the
end effector include a rotation actuator configured to actuate
rotation of the drill bit attachment.
5. The drilling apparatus of claim 3, wherein the actuators of the
end effector include a lateral motion actuator configured to
laterally move the end effector and drill bit outward and
inward.
6. The drilling apparatus of claim 5, wherein the lateral motion
actuator includes a rotary motor and a rotary-to-linear motion
converter configured to convert rotary motion of the rotary motor
into linear motion of the drill bit attachment and the drill
bit.
7. The drilling apparatus of claim 1, wherein an included angle of
the drill bit between the tip and the widest portion is between
50-degrees and 110-degrees.
8. The drilling apparatus of claim 1, wherein an included angle of
the drill bit between the tip and the widest portion is between
80-degrees and 100-degrees.
9. The drilling apparatus of claim 1, wherein the narrow flute
portion has a tapered configuration, beginning at the widest
portion of the drill bit and extending in a direction toward the
aftward end of the drill bit.
10. The drilling apparatus of claim 1, wherein the widest portion
of the drill bit has a smaller length than the narrow flute
portion.
11. The drilling apparatus of claim 1, further comprising a
position sensor communicably coupled with the control system and
configured for indicating proximity of the drill bit or end
effector to a workpiece to be drilled.
12. A drilling apparatus configured for drilling holes into a
composite workpiece, the drilling apparatus comprising: an end
effector including: an end effector housing, a drill bit attachment
extending outward from the end effector housing, a rotation
actuator coupled with the drill bit attachment and configured for
actuating rotation of the drill bit attachment, and a linear motion
actuator configured to actuate linear motion of the drill bit
attachment toward and away from the workpiece; a drill bit attached
to the drill bit attachment, wherein the drill bit includes a
forward end, an aftward end opposite the forward end, a tip formed
at the forward end, a widest portion aftward of the tip, and a
narrow flute portion aftward of the widest portion, wherein the
flute portion extends between the widest portion and the end
effector, wherein the flute portion has a smaller diameter than the
widest portion, wherein the widest portion has a smaller length
than the narrow flute portion; and a control system configured to
send control signals to the end effector commanding the end
effector to rotate the drill bit and commanding the end effector to
move laterally outward and inward, wherein the control system
commands the end effector to move laterally outward toward the
workpiece at a first speed and commands the end effector to move
laterally back inward away from the workpiece at a second speed,
wherein the second speed is faster than the first speed.
13. The drilling apparatus of claim 12, wherein the lateral motion
actuator includes a rotary-to-linear motion converter mechanically
configured to convert rotary motion into linear motion of the drill
bit attachment.
14. The drilling apparatus of claim 12, wherein an included angle
of the drill bit between the tip and the widest portion is between
80-degrees and 100-degrees.
15. The drilling apparatus of claim 12, further comprising a
position sensor communicably coupled with the control system and
configured for indicating proximity of the drill bit or end
effector to a workpiece to be drilled.
16. A method of drilling holes into a composite workpiece with a
drilling apparatus, the method comprising: actuating rotation of a
drill bit attachment with a drill bit attached therein; actuating
the drill bit attachment linearly toward the composite workpiece at
a first speed, thereby forming a hole through the composite
workpiece; and actuating the drill bit attachment linearly away
from the composite workpiece at a second speed, wherein the second
speed is greater than the first speed to limit an amount of time
that a relatively wider portion of the drill bit contacts the
workpiece during withdrawal of the drill bit from the composite
workpiece.
17. The method of claim 16, further comprising the step of clamping
the drill bit into the drill bit attachment prior to actuating
rotation of the drill bit attachment.
18. The method of claim 16, further comprising a step of a control
system positioning the drilling apparatus at a preselected
perforation location on the workpiece based on at least one of data
stored in and data accessed by the control system.
19. The method of claim 16, wherein the steps of actuating the
drill bit attachment linearly toward the composite workpiece and
linearly away from the composite workpiece are performed via a
lateral motion actuator, wherein the lateral motion actuator
includes a rotary-to-linear motion converter mechanically
configured to convert rotary motion into linear motion of the drill
bit attachment.
20. The method of claim 19, wherein actuating the drill bit
attachment linearly toward and away from the workpiece includes a
rotary motor, coupled with the rotary-to-linear motion converter,
rotating in a same single rotational direction for moving both
toward and away from the composite workpiece.
Description
BACKGROUND
[0001] Sandwich panels with perforated skins are typically
incorporated into aircraft engine nacelles to reduce the amount of
engine noise reaching the ground during flight. The perforated
skins include numerous holes, typically about 1 mm in diameter,
which cover between 5% and 10% of a nacelle panel's surface area.
This equates to roughly 1,000,000 holes in a single panel, and each
nacelle may contain multiple panels.
[0002] The holes may be molded into composite skins using pinmats,
but this process is labor and flow-time intensive, requires
pre-curing of the skin prior to assembly of the sandwich panel, and
necessitates tooling that would not otherwise be required. The
holes may also be formed by an abrasive erosion process, but this
too has drawbacks. Maskant must be applied to the skin manually,
and as with the pinmat process, the skin must be pre-cured prior to
assembly of the sandwich panel.
[0003] Mechanical drilling using a conventional drill bit overcomes
some of these limitations, as mechanically drilled holes may be
formed in a finished sandwich panel, thus eliminating separate
curing operations for individual skins. However, prior art drilling
equipment is too slow and expensive to cost-effectively drill the
large number of holes required. To meet desired production rates,
many expensive machines would be required, operating in parallel.
In addition to the expense, these machines would consume a large
amount of factory floor space and would increase the inventory that
must be maintained in-process at any given time.
[0004] Some perforating robots are much less expensive than
conventional drilling machines, and are also much more compact.
Unfortunately, these robots lack the precision and stability to
successfully serve as platforms for conventional drilling equipment
operated in conventional means.
[0005] Thus, there is a need for an improved apparatus and method
for perforating skins for nacelle sandwich panels.
SUMMARY OF THE INVENTION
[0006] Embodiments of the present invention solve the
above-mentioned problems and provide a distinct advance in the art
of nacelle sandwich panel fabrication. One embodiment of the
invention is a drilling apparatus having an end effector, a drill
bit attached to the end effector, and a control system. The drill
bit may include a forward end, an aftward end opposite the forward
end, a tip formed at the forward end, a widest portion aftward of
the tip, and a narrow flute portion aftward of the widest portion.
The flute portion may extend between the widest portion and the end
effector. The flute portion may also have a smaller diameter than
the widest portion. The control system may send control signals to
actuators of the end effector commanding rotation of the drill bit
and commanding the end effector to move the drill bit laterally
outward and inward.
[0007] In another embodiment of the invention, the end effector may
include an end effector housing, a drill bit attachment extending
outward from the end effector housing, a rotation actuator, and a
linear motion actuator. The rotation actuator may be coupled with
the drill bit attachment for actuating rotation of the drill bit
attachment. The linear motion actuator may actuate linear motion of
the drill bit attachment toward and away from the workpiece. The
drill bit may be attached to the drill bit attachment and may have
a forward end, an aftward end opposite the forward end, a tip
formed at the forward end, a widest portion aftward of the tip, and
a narrow flute portion aftward of the widest portion. The flute
portion may extend between the widest portion and the end effector,
and may have a smaller diameter than the widest portion.
Furthermore, the widest portion may have a smaller length than the
narrow flute portion. The control system may send control signals
to the end effector commanding the end effector to rotate the drill
bit and commanding the end effector to move laterally outward and
inward. In addition, the control system may command the end
effector to move laterally outward toward the workpiece at a first
speed and command the end effector to move laterally back inward
away from the workpiece at a second speed. The second speed may be
faster than the first speed.
[0008] In yet another embodiment of the invention, a drilling
apparatus described above may be implemented in a method of
drilling holes into a composite workpiece. The method may include
the steps of actuating rotation of a drill bit attachment and a
drill bit attached therein, then actuating the drill bit attachment
linearly toward the composite workpiece at a first speed, thus
forming a hole therethrough. The method may also include a step of
actuating the drill bit attachment linearly away from the composite
workpiece at a second speed that is greater than the first speed,
thus limiting the amount of time the widest portion of the drill
bit contacts workpiece while being withdrawn through the hole.
[0009] This summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the detailed description. This summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used to limit the scope of the claimed
subject matter. Other aspects and advantages of the current
invention will be apparent from the following detailed description
of the embodiments and the accompanying drawing figures.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0010] Embodiments of the current invention are described in detail
below with reference to the attached drawing figures, wherein:
[0011] FIG. 1 is a side view of a panel perforation drilling
apparatus constructed according to embodiments of the present
invention;
[0012] FIG. 2 is a perspective view of the drilling apparatus of
FIG. 1;
[0013] FIG. 3 is a perspective view of the housing of the drilling
apparatus of FIG. 1;
[0014] FIG. 4 is a perspective view of the drilling apparatus of
FIG. 1 with part of the housing removed;
[0015] FIG. 5 is an alternative embodiment of the panel perforation
drilling apparatus;
[0016] FIG. 6 is a side view of oval-shaped gears configured to
vary a lateral motion speed of a drill bit of FIG. 1;
[0017] FIG. 7 is a schematic view of a drill bit of the drilling
apparatus of FIG. 1;
[0018] FIG. 8 is a schematic view of an alternative embodiment of
the drill bit of FIG. 7;
[0019] FIG. 9 is a block diagram of the drilling apparatus of FIG.
1, including a control system communicatively coupled with
actuators which are mechanically linked to the drill bit and its
drill bit attachment; and
[0020] FIG. 10 is a flow chart illustrating a method of drilling
holes into a workpiece in accordance with embodiments of the
present invention.
[0021] The drawing figures do not limit the current invention to
the specific embodiments disclosed and described herein. The
drawings are not necessarily to scale, emphasis instead being
placed upon clearly illustrating the principles of the
invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] The following detailed description of the invention
references the accompanying drawings that illustrate specific
embodiments in which the invention can be practiced. The
embodiments are intended to describe aspects of the invention in
sufficient detail to enable those skilled in the art to practice
the invention. Other embodiments can be utilized and changes can be
made without departing from the scope of the current invention. The
following detailed description is, therefore, not to be taken in a
limiting sense. The scope of the current invention is defined only
by the appended claims, along with the full scope of equivalents to
which such claims are entitled.
[0023] In this description, references to "one embodiment", "an
embodiment", or "embodiments" mean that the feature or features
being referred to are included in at least one embodiment of the
technology. Separate references to "one embodiment", "an
embodiment", or "embodiments" in this description do not
necessarily refer to the same embodiment and are also not mutually
exclusive unless so stated and/or except as will be readily
apparent to those skilled in the art from the description. For
example, a feature, structure, act, etc. described in one
embodiment may also be included in other embodiments, but is not
necessarily included. Thus, the current technology can include a
variety of combinations and/or integrations of the embodiments
described herein.
[0024] A drilling apparatus 10 constructed in accordance with
embodiments of the present invention is illustrated in FIG. 1. The
drilling apparatus 10 is configured for drilling holes 12 into a
workpiece 14, such as composite aircraft panels and composite skin
of noise-reducing sandwich panels for an aircraft nacelle. However,
the workpiece 14 may be any other structure susceptible to drilling
without departing from the scope of the invention. The drilling
apparatus 10 may include an end effector 16, a drill bit 18
attachable to the end effector 16, and a control system 20 adapted
to execute method steps of a drilling process later described
herein.
[0025] As illustrated in FIGS. 1-4, the end effector 16 may include
an end effector housing 22, a drill bit attachment 24, a rotation
actuator 26 configured for rotating the drill bit attachment 24 and
the drill bit 18 therein, and/or a linear motion actuator 28
configured to provide linear motion toward and away from the
workpiece 14. The end effector housing 22, as illustrated in FIGS.
2-4, may support various components of the drilling apparatus 10
and may have any size, shape, or configuration to structurally
support those components during drilling operations. In some
embodiments of the invention, the end effector housing 22 may
include a monolithic unitary housing. Furthermore, as illustrated
in FIG. 4, the end effector housing 22 may include and/or attach to
an end effector carriage 30 supporting and stabilizing the drill
bit attachment 24 and actuators 26,28 described herein.
[0026] The drill bit attachment 24 may include a quill, drill
chuck, drill bit spindle, and/or any type of clamp rotatably
attached to the end effector housing 22 and suitable to hold the
drill bit 18 in radial symmetry therein. At least a portion of the
drill bit attachment 24 may extend outward from the end effector
housing 22 and may be supported thereby. At least a portion of the
drill bit attachment 24 may be actuatable at any desired drilling
speed via the rotation actuator 26, thereby rotating the drill bit
18. For example, the drill bit attachment 24 may spin the drill bit
18 at a rate of 50,000 to 100,000 rotations per minute, or
approximately 80,000 rotations per minute. However, other
rotational speeds may be used without departing from the scope of
the invention.
[0027] As illustrated schematically in FIG. 9, the rotation
actuator 26 may be coupled with at least a portion of the drill bit
attachment 24 and configured to rotate the drill bit 18 in a
clockwise and/or counterclockwise direction. The rotation actuator
26 may comprise a primary rotary motor, such as a continuously
variable motor, a servo motor, or the like. However, the rotation
actuator 26 may be any actuator used to automate rotation of drill
bits or other rotating tools known in the art without departing
from the scope of the invention.
[0028] The linear motion actuator 28 may be configured for
converting rotary motion into linear motion, thus driving the drill
bit 18 into the workpiece 14. Specifically, as illustrated in FIG.
9, the linear motion actuator 28 may include a secondary rotary
motor 32 or actuator and a rotary-to-linear motion converter 34
mechanically linked with the secondary rotary motor 32. The
rotary-to-linear motion converter 34 may be mechanically linked or
otherwise attached to provide linear motion to the drill bit
attachment 24. The rotary-to-linear motion converter 34 may
include, for example, a crank, a cam, a rack-and-pinion, or any
mechanical arrangements suitable for converting the rotary motion
provided by the secondary rotary motor 32 into linear motion of the
drill bit 18.
[0029] In some embodiments of the invention, the secondary rotary
motor 32 is a continuously-variable motor or servo motor which may
be controlled by the control system 20 to have a first speed of
linear insertion into the workpiece 14 and a second speed of linear
withdrawal when the drill bit 18 is pulled out, away from the
workpiece 14. The second speed may be faster than the first speed.
For example, servo feedback from the servo motor may be used by the
control system 20 or other circuitry to govern speed thereof
depending on angle readings or other position information obtained
via the servo feedback. Alternatively, a stepper motor may be used
to selectively switch the speed of the rotary-to-linear motion
converter 34 between two or more speeds. In yet another embodiment
of the invention, a cam with a predefined mechanical profile may be
used to switch the speed of the rotary-to-linear motion converter
34 and thus withdrawal the drill bit 18 at a faster speed than the
drill bit's insertion. In yet another embodiment of the invention,
as illustrated in FIG. 6, oval or oblong-shaped gears 38 may be
provided between the secondary rotary motor 32 and the
rotary-to-linear motion converter 34, such that the speed of linear
motion of the drill bit 18 is varied between the first speed and
the second speed at set intervals.
[0030] In some embodiments of the invention, the rotary-to-linear
motion converter 34 may allow the secondary rotary motor 32 to
continuously run in a single direction for both forward and
backward motion of the drill bit attachment 24 and/or the drill bit
18 toward and away from the workpiece 14. Because the secondary
rotary motor 32 does not need to reverse directions to retract the
drill bit 18 from the workpiece 14, this results in quicker
acceleration and eliminates any lag time present in prior art
systems during withdrawal of the drill bit 18 from the hole 12
created. However, other embodiments of the invention may include a
linear motion actuator 28 configured such that the secondary rotary
motor 32 does reverse directions to retract the drill bit 18 from
the workpiece 14. For example, as illustrated in FIG. 5, another
embodiment of the invention may include an apparatus 510
substantially similar or identical to apparatus 10 in many
respects, but with a crank stepper motor 532 and crank mechanism
534 operating as a linear motion actuator 528. In this embodiment
of the invention, the crank stepper motor 532 would reverse
directions for withdrawal of a drill bit 518 from a workpiece.
[0031] Alternatively, the secondary rotary motor 32 may be omitted
and the primary rotary motor of the rotation actuator 26 may be
used to both rotate the drill bit attachment 24 and/or drill bit 18
and to actuate the linear motion thereof via attachment with the
rotary-to-linear motion converter 34. In particular, a speed
reducing gear train or the like may be utilized between the
rotation actuator 26 and the rotary-to-linear motion converter 34.
Alternatively, the primary motor of the rotation actuator 26 could
be omitted and the secondary rotary motor 32 may be used to rotate
both the drill bit attachment 24 and/or the drill bit 18 and to
actuate the linear motion thereof via attachment with the
rotary-to-linear motion converter 34. Specifically, a
speed-increasing gear train or the like may be utilized between the
secondary rotary motor 32 and the drill bit attachment 24.
[0032] The drill bit 18, as illustrated in FIG. 7, may have a point
or tip 42, a widest portion 44, and a narrow flute portion 46. In
some embodiments of the invention, the drill bit 18 may also
include a shank 48 for attachment within the drill bit attachment
24. For example, the shank 48 may be positioned at an aftward end
of the drill bit 18 and the tip 42 may be positioned at a forward
end of the drill bit 18. An angle formed from the tip 42 to the
widest portion 44 may form a smaller included angle 50 than prior
art drill bits. Specifically, this included angle 50 may be
somewhere between 50-degrees and 110-degrees or between 80-degrees
and 100-degrees. In one example embodiment of the invention, this
included angle 50 may be approximately 90-degrees. Applicants have
discovered that, when compared with the 120-degree included angle
common in the drilling industry, this narrower included angle
reduces the force required during drilling, decreasing the relative
lateral or side-to-side motion between the drill bit 18 and the
workpiece 14.
[0033] The widest portion 44 may have a length smaller than the
flute portion 46 or may even merely be an edge at which the flute
portion 46 and the included angle 50 meet. The flute portion 46 of
the drill bit 18, between the shank 48 and the widest portion 44 of
the drill bit 18, may have a reduced diameter as compared to a
diameter of widest portion 44. For example, the flute portion 46
may taper from the widest portion 44 down to a narrower point
closer to or at the shank 48 positioned in the drill bit attachment
24. However, other shapes, profiles, or configurations of the flue
portion 46 having a smaller diameter than the widest portion 44 may
be used without departing from the scope of the invention.
[0034] The shank 48 as illustrated in FIG. 7 may have any diameter
sufficient to be secured within the drill bit attachment 24.
Because only the widest portion 44 of the drill bit 18 contacts the
workpiece 14 at boundaries of the holes 12 drilled thereby, and
only for a short amount of time, the drilling apparatus 10 is
better able to tolerate relative lateral or side-to-side motion
between the drill bit 18 and the workpiece 14. Specifically, for
much of the time during which the drill bit 18 is engaged with the
workpiece 14, there is clearance around the drill bit 18 within the
hole 12.
[0035] In one alternative embodiment of the drill bit 18, the flute
portion 46 may have a substantially uniform diameter from the
widest portion 44 to the shank 48, so long as the flute portion's
diameter is less than the diameter of the widest portion 44. For
example, as illustrated in FIG. 8, a drill bit 118 substantially
similar to drill bit 18, but with an arrow-like configuration, may
be used herein. The drill bit 118 may have a tip 142, a widest
portion 144, a flute portion 146 having a uniform diameter that is
smaller than the diameter of the widest portion, and a shank
148.
[0036] The control system 20, as illustrated in FIGS. 1 and 9, may
comprise any number or combination of controllers, circuits,
integrated circuits, programmable logic devices, computers,
processors, microcontrollers, or other control devices and
residential or external memory for storing data, status
information, position information, actuator speeds, and/or other
information accessed and/or generated by various components of the
drilling apparatus 10. The control system may further other
circuitry, sensors, connectors, and hardware known in the art. The
control system 20 may be electrically and/or communicably coupled
with the rotation actuator 26, the linear motion actuator 28,
and/or other sensors or circuitry of the drilling apparatus 10
through wired or wireless connections to enable information to be
exchanged between the various components. Wired connections may
include wires or other electrical connectors, fiber optic cables,
data buses, or the like. Wireless connections may include
transceivers, transmitters, receivers, antenna, wireless sensors,
and/or any other wireless communication devices known in the
art.
[0037] The control system 20 may implement a computer program
and/or code segments to perform some of the functions and method
described herein. The computer program may comprise an ordered
listing of executable instructions for implementing logical
functions in the control system. The computer program can be
embodied in any computer-readable medium for use by or in
connection with an instruction execution system, apparatus, or
device, and execute the instructions. In the context of this
application, a "computer-readable medium" can be any means that can
contain, store, communicate, propagate, or transport the program
for use by or in connection with the instruction execution system,
apparatus, or device. The computer-readable medium can be, for
example, but not limited to, an electronic, magnetic, optical,
electro-magnetic, infrared, or semi-conductor system, apparatus, or
device. More specific, although not inclusive, examples of the
computer-readable medium would include the following: an electrical
connection having one or more wires, a portable computer diskette,
a random access memory (RAM), a read-only memory (ROM), an
erasable, programmable, read-only memory (EPROM or Flash memory),
an optical fiber, and a portable compact disk read-only memory
(CDROM).
[0038] The features of the control system 20 may be implemented in
a stand-alone device, which is then interfaced to other components
of the drilling apparatus 10. The control features of the present
invention may also be distributed among the components of the
drilling apparatus 10. Thus, while certain features are described
as residing in the control system 20, the invention is not so
limited, and those features may be implemented elsewhere. The
control system 20 and computer programs described herein are merely
examples of computer equipment and programs that may be used to
implement the present invention and may be replaced with or
supplemented with other controllers and computer programs without
departing from the scope of the present invention.
[0039] In some embodiments of the invention, the control system 20
may include or may be communicably coupled with a position sensor
52 attached to the end effector housing 22 and configured to
provide the control system 20 with data regarding the end
effector's distance from the workpiece 14 along a z-axis and/or its
relevant position along a surface of the workpiece 14 along an
x-axis and/or a y-axis. For example, the position sensor 52 may be
a laser distance sensor configured to transmit information
corresponding to the end effector's distance from the workpiece 14
along a z-axis.
[0040] In use, the drilling apparatus 10 may be utilized for
performing a method for perforating or drilling holes into the
workpiece 14. The method may include clamping the drill bit 18,
having the narrow flute portion 46, as described above, into the
drill bit attachment 24. Next, the method may include the steps of
positioning the drilling apparatus 10 at a desired location
relative to the workpiece 14 and actuating the rotation actuator
26, thereby rotating the drill bit 18 about its axis. Then, the
method may include a step of actuating the drill bit 18 toward and
into the workpiece 14 at the first speed until the widest portion
has cleared the workpiece 14, such that space exists between
boundaries of the hole 12 formed thereby and the flute portion 46
of the drill bit 18. The method may further include a step of
actuating the drill bit 18 in a direction back through the hole 12
and away from the workpiece 14 at the second speed. The second
speed may be greater than the first speed.
[0041] Method steps for perforating or drilling holes into the
workpiece will now be described in more detail, in accordance with
various embodiments of the present invention. The steps of the
method 1000 may be performed in the order as shown in FIG. 10, or
they may be performed in a different order. Furthermore, some steps
may be performed concurrently as opposed to sequentially. In
addition, some steps may not be performed.
[0042] As illustrated in FIG. 10, the method 1000 for perforating
or drilling holes into the workpiece 14 may include clamping the
drill bit 18 into the drill bit attachment 24, as depicted in block
1002. The drill bit 18 may include the tip 42, the widest portion
44, and the narrow flute portion 46, as described above. Next, the
method 1000 may include the step of positioning the drilling
apparatus 10 at a preselected perforation location on the workpiece
14, as depicted in block 1004. The positioning of the drilling
apparatus 10 may be performed by one or more of the actuators 26,28
of the drilling apparatus 10 via instructions from the control
system 20 and/or proximity or location data received by the
position sensor 52 described above. Furthermore, the control system
20 may use CAD drawings or other such stored data to determine a
relative position on the workpiece for drilling one of the holes.
Note that other robotic joints and actuators known in the art, but
not described in detail herein, may be used to move the drilling
apparatus 10 into position without departing from the scope of the
invention. Additionally or alternatively, at least some positioning
of the drilling apparatus 10 may be performed manually by an
operator without departing from the scope of the invention.
[0043] The method 1000 may then include a step of actuating the
rotation actuator 26, as depicted in block 1006, thereby rotating
the drill bit 18 about its axis. Actuation of the rotation actuator
26 may be triggered by merely turning on or connecting electrical
power to the drilling apparatus 10 via an electrical plug, a
battery, and/or a switch, button, or the like. Additionally or
alternatively, actuation of the rotation actuator 26 may be
accomplished via instructions from the control system 20
communicated via wired or wireless communication channels to the
rotation actuator 26.
[0044] In addition, the method 1000 may include a step of actuating
the drill bit 18 toward and into the workpiece 14 at the first
speed, as depicted in block 1008, thereby plunging the drill bit 18
into the workpiece 14 until the widest portion 44 of the drill bit
18 has cleared the workpiece 14. Due to the design of the narrow
flute portion 46 described above, when the widest portion 44 clears
the workpiece 14, forming the hole 12 therethrough, space should
exist between boundaries of the hole 12 and the flute portion 46 of
the drill bit 18. Actuation of the drill bit 18 toward the
workpiece 14 may be performed by instructions provided from the
control system 20 to the linear motion actuator 28.
[0045] Finally, the method 1000 may include a step of actuating the
drill bit 18 in a direction back through the hole 12 and away from
the workpiece 14 at the second speed, as depicted in block 1010.
The second speed may be greater than the first speed. Specifically,
the control system 20 may send a control signal to the linear
motion actuator 28, commanding the linear motion actuator 28 to
increase the speed of the secondary rotary motor 32 to the second
speed. For example, this method step may include receiving a sensor
signal indicating a rotational location of the secondary rotary
motor 32, such that the sensor signal indicates a position at which
the drill bit 18 begins to retract in a direction away from the
workpiece 14. Alternatively, this method step may include the
control system 20 accessing rotational speed data stored therein or
sensed thereby, or any other data sufficient to calculate when the
secondary rotary motor 32 should increase to the second speed. In
some embodiments of the invention, as described above, step 810 may
be performed substantially automatically via cams or oblong-shaped
gears driven by the secondary rotary motor 32.
[0046] The drilling apparatus 10 and methods described herein
advantageously provide the benefits and conveniences of robotic
drilling while producing hole quality typical of slow and expensive
machine tools. Prior art drilling equipment tends to operate at
either a constant force or a constant feed rate. By allowing a
continuously variable feed rate profile, the drilling apparatus 10
enables a process that requires different rates at different parts
of the drilling cycle. By utilizing the rotary-to-linear motion
converter 34, the secondary rotary motor 32 actuating linear motion
of the end effector 16 and/or drill bit 18 is kept running in a
single direction, resulting in quicker acceleration and eliminating
any lag time present when reversing motor directions in prior art
systems during withdrawal of the drill bit from the hole 12
created.
[0047] Furthermore, the drilling apparatus 10 and methods described
herein are designed to minimize the time during which exterior
sides of the drill bit 18 are in contact with interior sides of the
holes created thereby. Specifically, applicants have discovered
that anytime there is contact between the sides of the holes and
the sides of the drill bit 18, relative motion between the drill
and the workpiece 14 may cause elongation of the hole 12.
Applicants have further discovered that this elongation requires
not only contact, but some amount of residence time. If
side-to-side contact between the drill bit 18 and hole 12 takes
place, a hole without significant elongation may still be produced,
provided that the duration of the contact is minimized. Due to
variations in the workpiece's thickness, positioning accuracy of
the workpiece 14, drill bit installation depth, robot accuracy, and
other factors, the drill bit 18 must be inserted into the workpiece
14 well beyond a point at which the hole 12 is fully formed. It is
during this extra insertion that the reduced diameter of the drill
bit 18 along the flute portion 46 provides clearance and prevents
side-to-side contact. When the drill bit 18 is withdrawn from the
hole 12, it will necessarily return the widest portion 44 of the
drill bit 18 to the hole 12, and for a time, no clearance will
exist during the withdrawal. However, the continuously variable
linear motion or feed capabilities of the end effector 16 permit
the extraction rate to be increased well beyond the rate used
during insertion of the drill bit 18 and hole formation. This
advantageously minimizes elongation during withdrawal.
[0048] Although the invention has been described with reference to
the embodiments illustrated in the attached drawing figures, it is
noted that equivalents may be employed and substitutions made
herein without departing from the scope of the invention as recited
in the claims.
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